Heretofore, magnetic cards, which record data employing a magnetic recording system, have widely been employed as, for example, identification cards (ID cards), credit cards, and the like. However, problems have occurred in which since in magnetic cards, it is possible to relatively easily rewrite data, data are not effectively secured from falsification, data are not well protected due to external magnetic effects, and further, the recording capacity is limited.
In some ID cards, for example, the surface comprises portrait (face image) as well as text information and the back surface comprises a writing layer capable of being manually written upon. It is possible to easily prepare such ID cards at low cost due to the recent progress of sublimation printing techniques. As a result, such ID cards have increasingly been employed for the past several years, but have not yet employed as a standard.
IC cards read and write data from external instruments and devices via electric contact points provided on the surface or a loop antenna in the card's interior. Compared to magnetic cards, IC cards have a greater storage capacity and exhibit a pronounced improvement in security. Specifically, non-contact type IC cards, which comprise in their interior an IC chip and an antenna which sends information to and receives information from the exterior, and has no electric contact points, exhibits excellent security compared to contact type IC cards having electric contact points on their surface, and have been employed for use in which data confidentiality as well as security against forgery and falsification are highly demanded in the same manner as in ID cards.
Conventional IC cards have been prepared employing the following methods. For example, IC parts as well as a wireless antenna are placed in container consisting of an upper and a lower cover, which have been prepared by plastic molding and the connecting surface of said upper and lower covers are adhered by thermally fusing. Alternatively, IC parts and a wireless antenna are placed in a groove which has been formed in a sheet material and are sealed employing resins. Subsequently, an image receptive layer holding sheet material is adhered thereon.
The IC cards, which are prepared employing the former method, when printed only with the definite codes without portrait and text information, are prepared at relatively low cost. However, when individual said IC cards are printed with different portrait and text information, it requires a manual operation in such a manner that after printing necessary information on a sheet material, employing a separate apparatus, the resultant sheet material is cut, and is then adhered onto a cover prepared by resin molding. As a result, the resultant IC cards become quite expensive.
In the latter method, a groove is formed in a sheet material. As a result, it is necessary to use a thick sheet material and to compensate for the increase in the thickness by decreasing the thickness of the image receptive layer holding sheet material. When the thickness of said image receptive layer holding sheet material is decreased, the surface of said sheet material corresponding to the portion sealed with resins becomes slightly concave when compared to the surface of the portion due to the difference in materials from the other portion sealed with resins as well as thermal contraction during curing. Due to that, when said image receptive layer is adhered onto the resultant sheet material, a concave portion corresponding to the concave portion of said sheet material is formed. As a result, when the portion above the antenna and IC is printed, color density is lowered or no printing occurs. Due to that, problems occur in which free presentation is limited in such a manner that it is required to carry out a layout on the surface of cards so that the concave portion of the image receptive layer is not printed. Further, even though the surface is smooth, it has been difficult to obtained desired printing characteristics due to the partial difference in heat conductivity. Specifically, from the viewpoint of image reproduction, major problems have occurred in which information comprised of image information such as a portrait image, having gradation characteristics, is printed employing a thermal transfer system.
Further, problems have occurred in which the visual appearance is degraded due to the identification of the position of IC chips when the IC card is exposed to light. In order to make it difficult to identify the IC chip position, the thickness of IC cards is increased to enhance a shielding effect. However, the resultant effect has not been sufficient. Problems have occurred in which the IC chip portion identified as above is destroyed to eliminate personal information so that card issuing industries are troubled.
Still further, when the card surface exhibits irregularities, the IC chip position is detected as noted above. Such IC cards cause problems in poor visual appearance as well as poor resistance against malicious acts.